BIOL 100 exam 2 - CH 20

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Trait

expressed characteristic

Allele

an alternative form of a gene.

determines the variation of a trait (i.e. blue eyes vs brown eyes)

Homozygous

2 copies of the same allele

Heterozygous

1 copy of one allele and 1 copy of a different allele

Dominant Allele

allele that shows up regardless if you have 1 or 2 copies

Recessive Allele

allele that can only be seen if there are 2 of them

Genotype

specific alleles that an individual has

"what it is"

Phenotype

the physical appearance of the "allele"

"what it looks like"

Pedigree

family tree of a trait expression

determination of ancestors' genotype

Carrier

person who has the gene but does NOT exhibit the trait

Complete Dominance

the dominant allele in a heterozygous person completely masks the recessive allele

Codominance

both alleles are expressed in a heterozygous individual

i.e. blood type ABO

Incomplete Dominance

heterozygous individual is a blend of 2 genes

i.e. Red Flower and White Flower make a Pink Flower

Pleiotropy

(ignore)

one gene having many effects

Multiple Alleles

3 or more alleles form a particular gene

i.e. the alleles governing the ABO blood types

Polygenic Inheritance

more than one gene controlling a single trait

i.e. height, skin color, eye color

X-Linked Genes

genes carried on the x chromosome

have no corresponding allele on the y chromosome

will be expressed in a male, and in a female (if she is homozygous)

Deletion

pertaining to chromosomes, the loss of a nucleotide or segment of a chromosome

Duplication

pertaining to chromosomes, the duplication of a region of a chromosome that often results from fusion of a fragment from a homologous chromosome

Amniocentesis

(ignore)

a method of prenatal testing for genetic problems in a fetus in which amniotic fluid is withdrawn through a needle so that the fluid can be tested biochemicallyand the cells can be cultured and examined for genetic abnormalities

Chorionic Villi Sampling (CVS)

(ignore)

a procedure for screening for genetic defects of a fetus by removing a piece of chorionic villi and examining the cells for genetic abnormalities

Law of Segregation

- During meiosis homologous pairs split

- 1 egg ends up with 1 set of alleles

- another egg could end up with another set of alleles

- i.e. any gamete is equally likely to have any allele (any combo is equally possible)

2 alleles

Every person has 23 pairs of chromosomes; therefore, each person has (#?) alleles for each trait.

Hybrid Crosses

utilizes 2 individuals to determine the inheritance pattern of a Single trait